Centimorgan

The centimorgan (abbreviated cM , named after Thomas Hunt Morgan ) is an auxiliary unit of measurement in genetics that indicates the frequency or probability of recombination in percent. In this way, the genetic distance can be quantified, i.e. the genetic distance between two loci on a chromosome .

Genes that are on the same chromosome can be "decoupled" by crossing over . The expected number of these cross-over events can be estimated from the (observed) recombination frequency.

Two loci are 1 cM away if the recombination (i.e. crossing over) probability between these loci is 1% per meiosis , i.e. on average there is a crossover in 100 meioses:

${\displaystyle \mathrm {Rekombination\,[cM]} =100\cdot {\frac {\mathrm {Zahl\;der\;rekombinierten\;Gameten} }{\mathrm {Gameten\;insgesamt} }}}$

(For the creation of a zygote you need two gametes , in each of which recombination may have taken place).

literature

• M. Hirsch-Kauffmann, M. Schweiger: Biology for physicians and natural scientists. Thieme, Stuttgart; 6th edition 2006. ISBN 978-3-13-706506-7
• H.Bickeböller, Ch. Fischer: Introduction to Genetic Epidemiology. Springer, 2007. ISBN 978-3-540-25616-8